Searching for novel complex materials with enhanced lithium-ion battery performances is one of the most challenging efforts.Many kinds of transition metal oxides and polyanionic frameworks were developed with various ...Searching for novel complex materials with enhanced lithium-ion battery performances is one of the most challenging efforts.Many kinds of transition metal oxides and polyanionic frameworks were developed with various structures,which can improve the energy density of lithium-ion batteries.In this work,we explored 4d and 4f transition metal La-Nb-O compounds as cathode materials for lithium-ion energy storage.Orthorhombic pyrochlore LaNb_(5)O_(14),orthorhombic perovskite LaNb_(3)O_(9),and monoclinic LaNbO_(4) compounds with different metal cation coordination polyhedra were synthesized using solid-state reaction.The orthorhombic pyrochlore LaNb_(5)O_(14) compound showed the highest capacity among these La-Nb-O compounds owing to its quasi‐2D network for Li‐ion incorporation.According to the electronegativity theory and ionic size,La^(3+)cations can form LaO12 polyhedra and hexahedral LaO_(8) units in different La-Nb-O compounds,which can stabilize octahedral NbO_(6) and/or pentahedral NbO_(7) and their assembled structures,resulting in easy lithium-ion diffusion.This work may provide some structure clues for the design of electrode materials for fast lithium storage.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.21601176)CAS-VPST Silk Road Science Found 2018(Grant No.GJHZ1854)+2 种基金the Youth Innovation Promotion Association,CAS(Grant No.2018262)Jilin Province Youth Talent Lifting Project(Grant No.181901)the Youth Talent Development Program of the State Key Laboratory of Rare Earth Resource Utilization(Grant No.RERUY2017004).
文摘Searching for novel complex materials with enhanced lithium-ion battery performances is one of the most challenging efforts.Many kinds of transition metal oxides and polyanionic frameworks were developed with various structures,which can improve the energy density of lithium-ion batteries.In this work,we explored 4d and 4f transition metal La-Nb-O compounds as cathode materials for lithium-ion energy storage.Orthorhombic pyrochlore LaNb_(5)O_(14),orthorhombic perovskite LaNb_(3)O_(9),and monoclinic LaNbO_(4) compounds with different metal cation coordination polyhedra were synthesized using solid-state reaction.The orthorhombic pyrochlore LaNb_(5)O_(14) compound showed the highest capacity among these La-Nb-O compounds owing to its quasi‐2D network for Li‐ion incorporation.According to the electronegativity theory and ionic size,La^(3+)cations can form LaO12 polyhedra and hexahedral LaO_(8) units in different La-Nb-O compounds,which can stabilize octahedral NbO_(6) and/or pentahedral NbO_(7) and their assembled structures,resulting in easy lithium-ion diffusion.This work may provide some structure clues for the design of electrode materials for fast lithium storage.
